% parameters to be specified:
% assume shape is organized in [dim_x, dim_y, dim_z]
shape = [101, 1001, 501];

c_model = zeros(shape);

% first specify regular-shaped regions
c_model(1:80, :, :) = 1500;               % close to water surface
c_model(81:101, :, :) = 5000;             % far from water surface


% then specify irregular-shaped regions

c_model(51:56, 301:330, :) = 5000;

% finally store this c model to file as binary
fp = fopen("../c_models/Sea1_local.c_model", "wb");
fwrite(fp, c_model, "double");